Tag: Research

A popular notion about transgender individuals is that sex-reassignment surgery reliably relieves the mental distress associated with being transgender. But researchers who have actually studied transgender individuals postsurgery have arrived at a different conclusion. As one investigator found, “even once the transsexual has achieved sex reassignment, the figure of being trapped in the wrong body, or being wrongly encased, continues to be evoked.”

Transgender adults who begin receiving hormonal therapy do benefit, on average, from that therapy: one year after starting hormonal therapy to transition to the desired gender, the rates of anxiety, depression, and impairment among transgender individuals are significantly reduced. Nevertheless, even after sex-reassignment surgery and hormone treatment, the rate of mental illness such as anxiety, depression, and bipolar disorder among transgender individual remains much higher than among the general population. “Sex reassignment is associated with more serious psychological sequelae and more prevalent regret than had previously been supposed,” conclude other reviewers. In the largest and longest follow-up available, researchers studied everybody who underwent sex-reassignment surgery in Sweden between 1973 and 2003: 191 MtF individual and 131 FtM individuals. These investigators found that 19 percent of MtF clients and 17 percent of FtM clients had been hospitalized for psychiatric problems prior to undergoing sex reassignment, compare with less than 4 percent of matched controls. After sex-reassignment surgery, transsexual clients were still nearly three times more likely than controls to be hospitalized for psychiatric problems other than gender dysphoria, even after adjustment for prior psychiatric problems. There was some benefit from sex-reassignment surgery, to be sure. Transsexuals who had undergone sex-reassignment surgery reported feeling less gender dysphoria – less of a sense of being trapped in the wrong body – and were somewhat less likely to be hospitalized for psychiatric problems than they were before the surgery.

But only somewhat. Even after sex-reassignment surgery, transsexual clients were still nearly five times more likely to have made a suicide attempt and nineteen times more likely to have died from suicide than were matched controls, again after adjusting for prior psychiatric problems. The researchers did not find any significant differences between MtF individual and FtM individuals on any of these outcomes. Being transgender, even in Sweden and even after having sex-reassignment surgery, puts you at much greater risk of having major psychiatric problems, including death by suicide. This finding is consistent with multiple other studies.

Professor Kim Wallen and his colleagues at the Yerkes National Primate Research Center in Atlanta decided to do this familiar study again, with a little twist: instead of offering human children a choice between dolls and trucks, they gave that choice to monkeys. They gave monkey the opportunity to play with a “boy toy” such as a truck or with a “girl toy” such as a doll.

The basic pattern of results was similar to the pattern seen with human children. The female monkeys slightly prefer to play with dolls rather than trucks. The males substantially prefer to play with trucks rather than dolls.

It is difficult to invoke the social construction of gender to accommodate this finding. You would have to assert that a monkey in authority, maybe a parent, is saying to a young male monkey, Don’t let me catch you playing with a doll! But in fact nothing of the sort happens. Monkeys don’t appear to care whether other monkeys, female or male, are playing with trucks or with dolls. And yet the main effect – the preference of the male to play with a truck rather than with a doll – is clearly present in monkeys, as it is in human children. But the social construction of gender cannot reasonably be invoked to explain this effect in humans, in view of the fact that a similar effect is present in monkeys…

Developmental psychologist Gerianne Alexander found sex differences among monkeys similar to the sex difference we see among human children. In 2003, one year after she published her monkey study. Professor Alexander published her theory explaining why female and male monkeys – as well as female and male humans – might prefer to play with different toys.

Scientists have known for more than thirty years that our visual system is actually two separate systems operating in parallel, beginning at the level of the ganglion cells in the retina and extending back to the visual cortex and visual association cortex. One system is devoted to answering the question What is it? What’s its color? What’s its texture? The other system is devoted to answering the question Where is it going? And how fast is it moving? These two systems in the brain are often referred to as the “what” and the “where” system.

Professor Alexander was the first to suggest that hardwired sex differences in the visual system may explain finding such as the observed sex difference is the toy preferences of children (as well as monkeys). She conjectured that maybe girls have more resources in the “what” system, while boys have more resources in the “where” system. Girls are more likely to play with a doll rather than with a dull gray truck because the doll has a more interesting color and texture. Boys are more likely to play with the dull gray truck because it has wheels. It moves.

Professor Alexander’s hypothesis helps to make sense of many finding that otherwise are hard to explain. For example, baby girls (three to eight months of age), but not baby boys of the same age, prefer to look at dolls rather than at toy trucks. When researchers show women and men different colors and ask them to name the colors, “women respond faster and more accurately than men.” When researchers test men and women to see how accurately they can target a moving object, men are significantly more accurate than women… Finally researchers in Germany have reported dramatic sex differences in the anatomy of the human visual cortex in adults, with significantly more resources devoted to the “where” system in men that in women, even after adjusting for any overall size difference in the brain.

In 2017, the Journal of Neuroscience Research devoted an entire issue to sex differences in every aspect of brain function, from vision to learning to mental illness. The issue was 791 pages long, with seventy-three different scholarly articles. Larry Cahill, a professor of neuroscience at the university of California at Irvine who served as editor for the special edition, wrote:

Due to a deeply ingrained, implicit (but false) assumption that “equal” means “the same,” most neuroscientists knew, and even feared that establishing that males and females are not the same in some aspect of brain function meant establishing that they were not equal. This assumption is false and deeply harmful, in particular to the health of women, but remains deeply impact nonetheless.

The past 15 to 20 years in particular witnessed an explosion of research (despite the prevailing biases against the topic) documenting sex influences at all levels of brain function. So overpowering is the wave of research that the standard ways of dismissing sex influences (e.g., “They are all small and unreliable,” “They are all due to circulating hormones,” “They are all due to human culture,” and “They don’t exist on the molecular level”) have all been swept away, at least for those cognizant of the research.

These papers forcefully document the fact that sex influences on brain function are ubiquitous, regularly reshaping findings – hence conclusions – at all levels of our field, and powerfully demonstrating how much “sex matters.”

The notion that sex matters fundamentally, powerfully, and pervasively for all of neuroscience (not just for reproduction) is an idea whose time indeed has come.

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This blog is a way of for me to organize quotes and selections, as well as some original content I have written. It is not specifically geared towards the public, but if you are interested in Torah, psychoanalysis, or philosophy you may come across something which is of interest. Any comments or discussion is welcome.